To the person skilled in the art there is known a card comprising electronic elements and formed of a shell in which are provided housings intended to receive such electronic elements and an outer protective layer which closes the housings.
There is also known a card having a symmetrical structure and formed of two shells substantially similar to one another, each of such shells having a structured surface serving to form housings intended to receive electronic elements when the two shells are assembled.
The method of manufacture of such latter card is generally the following:
initially, each shell is manufactured with the help of an injection technique, for example by hot moulding; PA1 secondly, the electronic elements are placed in one of the two shells and the other shell is thereafter placed on the first, the whole being assembled by a hot welding technique. PA1 IA) bringing, onto a work surface, a first outer layer formed by a solid material; PA1 IB) placing said electronic element on said first outer layer; PA1 IC) applying a binding material on said first outer layer; PA1 ID) bringing facing said first outer layer and onto said binding material a second outer layer formed of a solid material; PA1 IE) applying pressure on said first and second outer layers until such first and second outer layers are located at a predetermined distance relative to one another, said binding material then forming between such first and second outer layers a layer having a predetermined thickness.
Manufacture of the card described hereinbefore exhibits several difficulties.
In particular, following the hot assembly of the two shells, the electronic elements only partially fill the housings. This has as a consequence that the card exhibits fragile zones in places where the housings are situated, especially when the electronic elements incorporated in the card have relatively large dimensions. It is thus that when there is provided a coil of a diameter on the order of magnitude of the card, such a manufacturing method generates deformed zones (bulging or hollow) on the outer faces of the card such being naturally detrimental for the surface evenness of the card and for the printing which may be provided on the outer surfaces of such card.
There is further known from patent document EP-0 350 179 a method of manufacture of the card consisting in placing in a mould two outer layers and an electronic assembly, then injecting a filling material in liquid form in such mould. Once hardened, such filling material forms an intermediate layer between the two outer layers.
In order to increase the speed of production, two chains are provided, each comprising several half moulds coupled to one another. Such two chains are adapted to have a vertical motion and to form with two corresponding half-moulds belonging respectively to the two chains a mould exhibiting an opening at least on the upper part thereof in order to permit the filling thereof. Above the place where the two corresponding half-moulds are assembled to form a mould, there is provided a nozzle permitting the injection of the filling material in liquid form into the newly formed mould.
The method of manufacture of a card described hereinbefore is complicated. Additionally, for large production outputs, such method of manufacture necessitates substantial equipment which renders it burdensome.
It will be further noted that bringing in the electronic assembly and positioning it during the injection are in no manner described in the document considered here and are not evident. It is the same for bringing the outer layers into the half-moulds.
The card obtained by the method of manufacture described hereinbefore and such as described in patent document EP-0 350 179 is formed essentially of three layers, namely, an intermediate layer and two outer layers. Within the intermediate layer is provided an electronic assembly formed of electronic elements, a coil arranged on its own support and an interconnection support, such interconnection support serving to couple the electronic elements and the coil electrically and rigidly.
A major difficulty of such card arises from the fact that the interconnection support and the coil support increase the thickness of the card. Thus it is difficult to obtain a thin card having a thickness of 0.76 mm as prescribed by the ISO standard currently used for bank cards.
It will be noted furthermore that the method of manufacture proposed for such card does not assure that the interconnection support and the neighbouring outer layer are separated by a layer of filling material which is detrimental for good adhesion of such outer layer to the intermediate layer. Furthermore, such method of manufacture does not guarantee good positioning of the electronic assembly at the heart of the intermediate layer.
The present invention has as purpose to overcome the difficulties described hereinbefore in proposing a card with at least one electronic element included in the interior thereof and obtainable at a low manufacturing cost.